Begell House Inc.
Heat Transfer Research
HTR
1064-2285
37
5
2006
Intensification of Heat Transfer in Systems of Gas Impact Jets
375-382
B. P.
Zhilkin
Ural State Technical University − UPI, Ekaterinburg, Russia
A. V.
Zaitsev
Ural State Technical University − UPI, Ekaterinburg, Russia
It is shown that application of irregular systems of nozzles with the cross section of asymmetric shape makes it possible to substantially increase the efficiency of heat transfer in gas impact jets. The dependences of the average coefficient of heat transfer, energy efficiency, and of the quality of heat transfer on the geometric and operational parameters of jet systems are considered.
Heat Transfer in a Transverse Extended Cavity with Inclined Walls in a Turbulized Flow
383-394
A. Yu.
D'yachenko
S. S. Kutateladze Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Nadezhda I.
Yarygina
S. S. Kutateladze Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Viktor I.
Terekhov
Kutateladze Institute of Thermophysics, Laboratory of Thermal and Gas Dynamics, Russian Academy of Sciences, Siberian Branch, 630090,1, Acad. Lavrent'ev Avenue, Novosibirsk, Russia; Novosibirsk State Technical University, K. Markx av., 20, Novosibirsk, 630073, Russia
Experimental investigations of the influence of an external degree of turbulence on heat transfer intensification in a cavity with a small aspect ratio, with the angles of inclination of the lateral walls being varied from 30° to 90°, were carried out. It is shown that in a rectangular cavity the average heat-transfer rate over the surface at a turbulence level Tu0 of 6.5% increases by a factor of 1.2, whereas at Tu0 = 16% − by a factor of 1.4. The visualization of the patterns of vortex formation has shown that at angles φ = 60° or 70° the flow becomes extremely unstable, depending on the Reynolds number. For these angles one observes a marked enhancement of heat transfer which is strengthened at a high flow turbulence.
Natural Convection Heat Transfer in a Rotating Enclosure with Three Rows of Discrete Heat Sources
395-405
L. F.
Jin
School of Mechanical and Production Engineering, Nanyang Technological University, Singapore 639798
C. P.
Tso
School of Mechanical and Production Engineering, Nanyang Technological University, Singapore 639798
K. W.
Tou
School of Mechanical and Production Engineering, Nanyang Technological University, Singapore 639798
A numerical study of air-filled slowly rotating enclosure with three rows of discrete heat sources is made. The enclosure rotates around its longitudinal horizontal axis. Three physically realizable phenomena, uniperiodic oscillation, multiperiodic oscillation, and chaotic oscillation are identified numerically. In the cases of stationary or low rotation speed, buoyancy force causes clockwise and counterclockwise circulations, and correspondingly there are three or two local peak Nusselt numbers in each periodic oscillation. With increasing rotation, clockwise circulation is enlarged and tends to dominate the counterclockwise circulation. The second and third peak Nusselt numbers become weakened and negligible. In a stationary case, heat transfer behavior for the heaters of the top row and bottom row is symmetrical, but with an increase in the speed of rotation, it gradually becomes asymmetrical.
Use of Asymptotic Methods in Studying the Temperature Field in the Operating Well
407-419
A. I.
Filippov
Sterlitamak Branch of Bashkortostan Academy of Sciences, Sterlitamak, Russia
P. N.
Mikhailov
Sterlitamak Branch of Bashkortostan Academy of Sciences, Sterlitamak, Russia
K. A.
Filippov
Sterlitamak Branch of Bashkortostan Academy of Sciences, Sterlitamak, Russia
An asymptotic solution of the problem on the temperature field in the operating well bore has been constructed in zero and first approximations. It has been shown that zero approximation corresponds to the temperature values average over the cross section of the well, while the first approximation describes radial distributions. Solutions have been built for a random axisymmetric velocity profile. Formulas have beenobtained and space-time distributions of temperature have been calculated.
Modeling and Computation of Heat Transfer in a System "Body-Multilayer Coating"
421-433
V. A.
Shevchuk
Ya. S. Podstrigach Institute of Applied Problems of Mechanics and Mathematics, National Academy of Sciences of Ukraine, L'vov, Ukraine
A technique for approximate calculation of the heat-conduction process in structural elements with thin multilayer coatings has been developed. This technique is based on a substantially simplified solution of the initial problem and is related to modeling of coating by thin-wall shells with relevant geometrical and thermophysical properties of the coating. With such approach, the impact of thin coatings on heat transfer in the system "body-coating" is described by generalized boundary conditions. The efficiency of the proposed approach is illustrated by comparing the results, obtained by its application, with the results of an accurate solution of the test problem − heating of the cylinder with a three-layer coating.
Development of the Methods of Combinatorial Thermal Modeling on the Basis of Object-Oriented Programming
435-446
V. S.
Khokhulin
Moscow Aviation Institute (State Technical University), Moscow, Russia
A. A.
Balashov
Moscow Aviation Institute (State Technical University), Moscow, Russia
Dmitry M.
Titov
Moscow Aviation Institute, 4 Volokolamskoe Hgw., Moscow, 125993, Russia
I. A.
Selyanova
Moscow Aviation Institute (State Technical University), Moscow, Russia
The main content of combinatorial mathematical modeling of thermal modes in various structures is described. It is demonstrated that building and processing of complex data structures in the process of combinatorial modeling can be fully implemented in modern programming environments on the basis of object-oriented programming.
Conditions of the Existence of the Optimum Thickness of a Screened Wall Exposed to Local Pulse-Periodic Heating
447-457
E. S.
Tverskaya
N. E. Bauman Moscow State Technical University, Moscow, Russia
The work has defined sufficient conditions for existence of an optimal thickness of a flat isotropic wall, ensuring a minimum steady-state temperature of its most heated point, with the use of a thermal insulator and thermally active gasket operating on the feedback principle.
Thermal Interaction of Straight-Through and Twisted Gas Jets with a Crossflow
459-466
B. I.
Zyskin
Ural State Technical University − UPI, Ekaterinburg, Russia
S. S.
Skachkova
Ural State Technical University − UPI, Ekaterinburg, Russia
K. V.
Zaitsev
Ural State Technical University − UPI, Ekaterinburg, Russia
B. V.
Berg
Ural State Technical University − UPI, Ekaterinburg, Russia
T. F.
Bogatova
Ural State Technical University − UPI, Ekaterinburg, Russia
B. P.
Zhilkin
Ural State Technical University − UPI, Ekaterinburg, Russia
The thermal structure of straight-through and twisted gas jets developing in a stalling flow has been revealed experimentally. The data obtained have been correlated in the form of equations for dimension-less parameters with the aid of a modified Cassini oval.